Humans may be wired to seek out new experiences, according to a study published Wednesday in the online edition of the journal Neuron[Wittmann et al., 2008].

...

During the study, [Bianca] Wittmann and her colleagues looked at people's brain activity through functional magnetic resonance imaging (fMRI)...

When people chose new images, Wittmann says that an area deep in the brain called the ventral striatum lit up on the fMRI scans. The ventral striatum is thought to be involved in emotions and behavior, including addictions.

"When people shoot up stimulant drugs like cocaine, they tend to trigger activity in this system," [Dr. David] Spiegel says.

When activated, nerve cells in the ventral striatum release a chemical called dopamine, which stimulates feelings of enjoyment and pleasure.

Even for the average person, not just people who use drugs, Wittmann says that the emotions brought about by the release of dopamine are "a large part of what keeps us going and what makes us get up in the morning"; they are our internal reward system for certain behaviors.

It may be these feel-good sensations that caused the participants to keep selecting the new images.

Because choosing a new picture in a psychology experiment is just like intravenous cocaine...

The goal of this ‘dialogue style’ review (which loosely follows a series of question and answer e-mails between the authors) is to make clear to those not versed in reinforcement learning theory what temporal difference prediction errors are and how this theory interacts with neuroscientific research.

Q5: The influential reward prediction error hypothesis of dopamine arose from comparing monkey electrophysiological data to the characteristics of a TD prediction error (Schultz et al., 1997). Today, other forms of neural recordings have targeted this same signal. What are the basic criteria for establishing that a recorded signal is, indeed, a TD prediction error?

Three criteria can be considered the ‘fingerprint’ of a reward prediction error signal: a phasic increase to unexpected rewards (a positive prediction error), no change to predicted rewards and a phasic decrease (a negative prediction error) when an expected reward is omitted (or vice-versa – decreases to positive errors and increases to negative errors).

Figure 1 (Niv & Schoenbaum, 2008). The time course of the reward, value and prediction error signals in the TD model. The first predictive stimulus is the label on the wine bottle, after which wine is poured into the glass and finally consumed. Cue-related phasic neural signals whose magnitude reflects the future predicted reward can be called prediction error signals, but sustained neural signals corresponding to the value of the predicted reward throughout the trial are designated value signals.

...although the authors acknowledged that such signals can also occur elsewhere in the brain. Yet, Niv and Schoenbaum are critical of these latter activations observed in neuroimaging studies:

Q8: Correlates of prediction errors in functional imaging studies are frequently found not in the midbrain but, rather, in areas such as the striatum, amygdala, and orbitofrontal cortex. Do all these areas signal prediction errors?

This is a tricky issue that has caused much confusion. Imaging studies have indeed found blood-oxygen-level level dependent (BOLD) signals that correlate with a precise, computationally derived TD prediction error in a variety of brain areas. Furthermore, a handful of single-unit recording studies have reported that activity in other brain areas – amygdala, striatum, orbitofrontal cortex and elsewhere – is reliably modulated by whether rewards or punishments are expected...

However, current thought has it that the BOLD signal does not directly reflect firing activity in an area but, rather, correlates with the local field potential and local processing, which are driven by subthreshold activity and synaptic inputs to the area. Thus, perhaps it is appropriate to view the imaging results as reflecting the information that an area is receiving and processing, whereas single-unit activity reflects the information that an area is transmitting to downstream regions.

The recognition that computational ideas from reinforcement learning are relevant to the study of neural circuits has taken the cognitive neuroscience community by storm. A central tenet of these models is that discrepancies between actual and expected outcomes can be used for learning. Neural correlates of such prediction-error signals have been observed now in midbrain dopaminergic neurons, striatum, amygdala and even prefrontal cortex, and models incorporating prediction errors have been invoked to explain complex phenomena such as the transition from goal-directed to habitual behavior. Yet, like any revolution, the fast-paced progress has left an uneven understanding in its wake. Here, we provide answers to ten simple questions about prediction errors, with the aim of exposing both the strengths and the limitations of this active area of neuroscience research.

Since PNAS is not, to my knowledge, a true peer-reviewed journal. I've decided to post a little review of the article addressing its validity.

[NOTE: that is not entirely true. Read the footnote1 for an explanation.]

Shusaku continues with this biting critique:

1) Structural MRI measruements - the regions of interest (ROIs) demarcated in this study included the ventricles, which are not gray or white matter. This indicates that the measurements of structural asymmetry can easily be confounded by differences in ventricular size. In which case, it is equally likely gray or white matter asymmetry cannot be determined by the results presented. There result of differences in structural asymmetry are further undermined by the fact that the cerebellum demarcations only contain gray/white matter and show no differences in asymmetry between subject groups.

Given the apparent specificity of differences in male and female cognitive advantages, and regional specificity of brain–behavior relationships, global differences in brain size between the sexes that have been readily observed with relatively gross methods might not be the most relevant structural dimorphism when investigating neural substrates of sex differences in cognition.

This is a very important point, because a major result in their study was that gray matter thickness in the right inferior parietal and posterior temporal cortices was 0.45 mm thicker in women than in men [all of unknown sexual orientation], as illustrated below.

Fig. 1 (Sowell et al., 2007). (A) Maps of differences between the sexes in thickness of gray matter (males coded 1, females coded 0 for all maps displayed) for the entire group of 176 subjects showing differences in gray matter (in millimeters) between the male and female subjects according to the color bar on the right. Warmer colors (less than 0 on the color bar) are regions where gray matter thickness is greater in the female than in the male subjects, and cooler colors (greater than 0) are regions where the males have greater gray matter thickness than the female subjects. Note the approximately 0.45 mm increase in cortical thickness in females in the right posterior temporal lobe.

And that's only by way of illustrating Shusaku 's point #1contra Savic and Lindström. He also criticized the amygdala functional connectivity analysis (a whole 'nother topic), the assumption that learning and environment cannot account for the results, and the exclusion of bisexuals (although all studies seem to exclude them, so that one's not really fair).

There are many more technical problems with the analytical techniques used in this study. I'm not going to bother going through all of them. Needless to say, this study proves absolutely nothing, and is just another example of bad science. As an MRI researcher, this article offends me personally, for it gives MRI and PET research a bad rap; I'm going to go throw up now.

Footnote

1 There are multiple routes to publishing in PNAS. One track is direct submission to the editors, who send it out for peer review. Another track is for a member of the National Academy of Sciences to either sponsor ("communicate") a paper by other authors or to submit ("contribute") his/her own paper (both without peer review from the PNAS Editorial Board). Savic and Lindström submitted to the Editorial Board, so the paper did go out for peer review. However, I noticed something that's not usually allowed, i.e., the acting Editor for the manuscript is affiliated with the same institution as the authors (Karolinska Institutet).

Harold Mouras, at University of Picardie Jules Verne in Amiens, France, and his colleagues wanted to understand the cerebral underpinnings of visually-induced erections.

They suspected there might be a role for mirror neurons, a special class of brain cell that fires both when people perform an action and when they observe it being performed.

The researchers invited eight young men into the lab and asked them to view three types of video clips. Along with late-night fishing documentaries and snippets of Mr Bean, the volunteers got to see erotic videos of [XXX]...1

This isn't the first study to invoke the specter of mirror neurons as a critical aspect of responsiveness to viewing porn. Ponsetti et al. (2006) showed pictures of male and female sexually aroused genitals to gay and straight male and female participants [see An "Endophenotype" For Sexual Orientation? for a full description of that study]. The authors summarized their results as follows:

a mirror neuron is a neuron which fires both when an animal performs an action and when the animal observes the same action performed by another (especially conspecific) animal. Thus, the neuron "mirrors" the behavior of another animal, as though the observer were himself performing the action.

The Neurocritic is as skeptical as anyone about the mirror neuron craze, but if the PMv activity in this experiment is really imitative in nature, or even "empathetic" (instead of motor imagery or motor preparation), then wouldn't same-sex genitals elicit greater activity than opposite-sex genitals, regardless of sexual orientation?

To investigate the hypothesis that the activation of the mirror-neuron system could be part of the neural mechanisms regulating visually-induced sexual arousal, including the erectile response, we examined whether the response of the mirror-neuron system to sexually stimulating video clips is correlated with the erectile response of healthy volunteers.

The participants were ten healthy heterosexual males somewhere between the ages of 18 and 60. The authors hypothesized that

a neural pathway linking the mirror-neuron system to neural structures controlling erection could be represented by the efference of the frontal operculum – a region containing mirror neurons - to the insula.2

The ventral premotor cortex in Brodmann area 6 is posterior to the frontal operculum (Tomassini et al., 2007). Do we really know that the frontal operculum contains mirror neurons? The most [only]definitive evidence for mirror neuron-type activity is from single-unit recording, not from fMRI. Do monkeys even have a frontal operculum? Yes, but it seems to be mostly gustatory.

Vilayanur Ramachandran, at the University of California at San Diego, who also studies mirror neurons, calls it a "bold" study, and congratulates the group on defying the taboo on studying human sexual physiology.

While he thinks it is perfectly plausible that mirror neurons play a role in how porn turns us on, he says more needs to be done to understand what that role is. For a start, he says, a large number of the brain's structures seem to be involved, not just the pars opercularis, and the interaction between these regions in response to porn is unclear.

"It doesn't give you an experimental lever into the problem," he adds.

And while Ramachandran agrees that the timing of mirror neuron activation and erection is probably critical, fMRI isn't accurate enough to show clearly what is going on with these brain regions over such short time frames.

Ramachandran isn't usually one to show restraint in interpreting data, but here he's right that the BOLD signal was correlated positively with the plethysmographic signal in multitude of brain regions. The authors focus on Frontal operculum, Precentral gyrus, Middle frontal gyrus, Postcentral gyrus, Inferior parietal lobule, Postcentral sulcus, Supramarginal gyrus, Anterior insula, and Posterior insula in the main body of the text, but one can...

(see exhaustive list of regions in Tables 1 and 2 of the online electronic supplementary material)

...once they're online (they're not yet).

ADDENDUM: My criticism of this statement, "Pars opercularis (Brodmann area [BA] 44) is a likely homologue of a subdivision of area F5 of monkeys" appears to be justified. In a recent review of 24 fMRI studies, Morin and Grèzes (2008) discovered that

Observing biological actions with a physical target, compared to a visual control showing no action at all, consistently activated the ventral premotor cortex (BA 6), and did so significantly more than observing target-less actions (with the same control). In contrast, the activity in BA 44 ("Broca’s area") was not modulated by the presence or absence of targets. We propose that the ventral precentral gyrus, and not BA 44, shares the visual properties of "mirror" neurons found in area F5 of the macaque brain.

Footnotes

1 Edited to avoid search engine hits to this blog from terms like "s*roking n**ed women, enjoying f***atio and engaging in interco**se."

MOURAS H, STOLERU S, MOULIER V, PELEGRINI-ISSAC M, ROUXEL R, GRANDJEAN B, GLUTRON D, BITTOUN J. (2008). Activation of mirror-neuron system by erotic video clips predicts degree of induced erection: an fMRI study. NeuroImage DOI: 10.1016/j.neuroimage.2008.05.051.Although visually-induced erection is a common occurrence in human male behaviour, the cerebral underpinnings of this response are not well-known. We hypothesized that the magnitude of induced erection would be linearly correlated with the activation of the mirror-neuron system in response to sexually explicit films. When presented with sexual video clips, eight out of ten healthy subjects had an erectile response demonstrated through volumetric penile plethysmography. The level of activation of the left frontal operculum and of the inferior parietal lobules, areas which contain mirror neurons, predicted the magnitude of the erectile response. These results suggest that the response of the mirror-neuron system may not only code for the motor correlates of observed actions, but also for autonomic correlates of these actions.

While the results were striking, they would be more convincing if the authors had matched the groups for IQ, education and measures of depression and anxiety, said Suzanne Corkin, a professor of behavioral neuroscience at the Massachusetts Institute of Technology, in an e-mailed statement. Also, the authors are "overly dismissive'' of the potential role of environmental influences, Corkin said.

"In short, I would be reluctant to draw strong conclusions about heterosexual versus homosexual brain structure and connectivity from this single experiment,'' Corkin said. She wasn't involved in the study.

That quote came from an article written by Elizabeth Lopatto, which is commendable for interviewing experts and providing background on the subject. Read the whole article (excerpt below).

June 16 (Bloomberg) -- Gay men and straight women share brain characteristics that suggest sexual preferences may be innate rather than learned, researchers said. Lesbians and heterosexual men also had similar brain tendencies.

A study of 90 adults showed similarities between gay men and straight women in a part of the brain linked to emotional response called the amygdala, and a similar finding for lesbians and straight men. The research also found lesbians and heterosexual men had larger right brains, the side associated with spatial ability, while the left and right brains of both gay men and straight women were more symmetrical.

The study, published in the Proceedings of the National Academy of Sciences, adds to research that suggests a biological basis for homosexuality, researchers said. Earlier studies have mostly focused on behavioral differences and similarities.

‘...how narrow [banausisch] a matter it would be if there were cells of morality and immorality, such as virtue cells, murder cells, or cells responsible for rage. Things will surely be more complicated.’

The localization of morality was discussed with equal reserve. Criminal anthropologists who looked eagerly for neurological and biological mechanisms to explain human immorality and criminal behaviour unanimously denied the existence of an isolated moral centre or moral organ that might be pathologically damaged. The French criminal anthropologists Gabriel Tarde and Alexandre Lacassagne dismissed the idea of a localizable moral sense as impossible or even ridiculous (Lacassagne, 1908: vii; Tarde, 1899: 240). ... Hans Kurella firmly asked that criminal anthropology should entirely abandon old-fashioned concepts such as an innate conscience, whether it was thought of as a localizable brain centre or not (Kurella, 1893: 204).

But really, the occipital lobes? Where did he get that idea? Verplaetse (2004) continues, quoting Benedikt:

When I freed the first brain (the brain of a robbing murderer) from the cranial cavity, his crime became clear to me with an unprecedentedly anatomical transparency. The occipital lobes did not cover the cerebellum and in this discovery I discerned the crucial distinction between man and animal.

...researchers at the California Institute of Technology have discovered that reason struggles with emotion to find equitable solutions, and have pinpointed the region of the brain where this takes place. The concept of fairness, they found, is processed in the insular cortex, or insula, which is also the seat of emotional reactions.

"The fact that the brain has such a robust response to unfairness suggests that sensing unfairness is a basic evolved capacity," notes Steven Quartz, an associate professor of philosophy at Caltech and author of the study, voicing a sentiment that anyone who has seen children fight over a treat can relate to.

"The movement to look into the neural basis for ethical decision making is only about seven years old," Quartz adds. "This is the first study where people made real decisions with real consequences."

So the insula is the seat of emotional reactions!! And investigations of the neural basis for ethical decision making are only 7 years old!

According to Wikipedia, the insula "lies deep to the brain's lateral surface, within the lateral sulcus which separates the temporal lobe and inferior parietal cortex. These overlying cortical areas are known as opercula (meaning "lids"), and parts of the frontal, temporal and parietal lobes form opercula over the insula."

It's a pretty large area. Besides being crowned the "seat of emotional reactions" (whatever that means), portions of the insula have been associated with interoceptive awareness, visceral sensation, pain, autonomic control, and taste, among other things... a lot of other things. Do a search of the BrainMap database using just two of the many insular foci reported by the Caltech researchers and you'll see activations related to action execution, speech, attention, language, explicit memory, working memory, and audition.

...how goods and benefits should be dispersed throughout a society in a fair and just manner. As an extreme example of this dilemma, imagine you are commissioned to deliver 100 lbs. of food to a famine-stricken region that consists of two villages a hundred miles apart. If you deliver half of the food to the first village, then travel to the second, 30 lbs. of the food will spoil during the trip...

Philosophers have offered several solutions to debates of this nature. Utilitarianism... asserts that one’s primary goal should be the achievement of a maximal amount of good or happiness. In the situation described above, a utilitarian might opt to deliver all of the food to the first village. ..... Another approach to such a quandary is known as deontological ethics, which emphasizes not the consequences of one’s actions, but whether the actions are right or wrong, just or unjust. From a deontological perspective, it would be unjust to distribute the food unequally.

To examine the trade-off between equity and efficiency, Hsu et al. (2008) devised a task in which the participants decided on how to allocate money to children living in an orphanage in northern Uganda.

In each trial, participants decided whether varying allocations of money, denominated in meals, would be taken away from either of two groups of children; the participant’s choice was to decide from whom to take.

You can see an example of an experimental trial in this must-see movie from the paper's Supporting Online Material (embedded below).

Movie s2No Switch Trial. Illustration of a trial where the subject does not switch the lever. Animation speed is increased for illustration purposes. See Fig. 1 for actual duration of events and screens.

During the Switch, insular activity was correlated with the level of inequity, but so was activity in the right postcentral gyrus and the medial frontal gyrus (Table S12). Before the Switch (during the Display), inequity correlated with insular activity and with activity in R Brodmann area 10, L inferior temporal gyrus, R medial frontal gyrus, L posterior cingulate, L BA 39, R superior temporal gyrus, R precuneus (Table S11)... I needn't go on.

The authors conclude:

Against utilitarianism, our results support the deontological intuition that a sense of fairness is fundamental to distributive justice but, as suggested by moral sentimentalists, is rooted in emotional processing. More generally, emotional responses related to norm violations may underlie individual differences in equity considerations and adherence to ethical rules.

...rationalization of inequality statistically mediates the relationship between conservatism and happiness. In other words, it suggests that at least part of the reason conservatives are happier than liberals is that they're more likely to rationalize inequality.

But did we need fMRI to tell us that? Is it really all in the insula? Couldn't we have more or less learned the same thing by obtaining peripheral autonomic measures, like heart rate, blood pressure, and skin conductance?

Wednesday, June 11, 2008

DRINKING a cup of coffee can wake you up, but perhaps just a whiff of Java is enough to reverse the effects of sleep deprivation on the brain.

A team led by Yoshinori Masuo at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, deprived rats of sleep for a day. When they examined their brains they found reduced levels of mRNA - messenger molecules that indicate when a gene is being expressed - for 11 genes important to brain function. When the rats were exposed to the aroma of coffee, the mRNA for nine of the genes was restored to near normal levels, and pushed to above normal levels for two - GIR, involved in neuro-endocrine control, and NFGR, thought to control oxidative stress (Seo et al., 2008).

We don't know if the same genes are suppressed in sleep-deprived humans, nor whether we would feel tired if they were [NOTE: but that won't stop us from wild speculation], but many of these genes do have human equivalents. So the team says gene suppression may help explain why people feel bad when they haven't had enough sleep - and that gene reactivation could explain why people love the smell of coffee. [NOTE: did the team inhale a little too much coffee bean aroma?]

Next the team hopes to identify the molecules in coffee aroma that affect gene expression. They suggest pumping them into factories to help revive tired workers who can't sip coffee while operating machinery.

The aim of this study was 2-fold: (i) to demonstrate influences of roasted coffee bean aroma on rat brain functions by using the transcriptomics and proteomics approaches and (ii) to evaluate the impact of roasted coffee bean aroma on stress induced by sleep deprivation. The aroma of the roasted coffee beans was administered to four groups of adult male Wistar rats: 1, control group; 2, 24 h sleep deprivation-induced stress group (the stress group); 3, coffee aroma-exposed group without stress (the coffee group); and 4, the stress with coffee aroma group (the stress with coffee group). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of some known genes responsive to aroma or stress was performed using total RNA from these four groups. A total of 17 selected genes of the coffee were differently expressed over the control. Additionally, the expression levels of 13 genes were different between the stress group and the stress with coffee group: Up-regulation was found for 11 genes, and down-regulation was seen for two genes in the stress with coffee group. We also looked to changes in protein profiles in these four samples using two-dimensional (2D) gel electrophoresis; 25 differently expressed gel spots were detected on 2D gels stained by silver nitrate. Out of these, a total of nine proteins were identified by mass spectrometry. Identified proteins belonged to five functional categories: antioxidant; protein fate; cell rescue, defense, and virulence; cellular communication/signal transduction mechanism; and energy metabolism. Among the differentially expressed genes and proteins between the stress and the stress with coffee group, NGFR, trkC, GIR, thiol-specific antioxidant protein, and heat shock 70 kDa protein 5 are known to have antioxidant or antistress functions. In conclusion, the roasted coffee bean aroma changes the mRNA and protein expression levels of the rat brain, providing for the first time clues to the potential antioxidant or stress relaxation activities of the coffee bean aroma.

"Using recorded brainwave activity and eye movements during REM sleep to determine robot behaviors and head positioning, 'Sleep Waking' acts as a way to 'play-back' dreams. Through this piece we hope to investigate one of the possible human-robot relationships."

In a personal highlight, The Neurocritic was crowned the "neuroblog-sovereign of sarcasm," a honor to place alongside a wonderful review in the February 2008 issue of Scientific American Mind: "always sardonic (and occasionally scathing)."

The very-banned 1987 film Superstar: The Karen Carpenter Story by Todd Haynes depicts her life and illness. He was sued by her brother and by their record company and the film will not be legally distributed again... Superstar is unique in using Barbie-like dolls as actors. You might not imagine that method would create such sympathy and poignancy, but it's a brilliant and powerful film.

However, Mind Hacks informs us that the torrent has been, well, banned again.

Therefore, I also suggest you watch the music video for Tunic (Song for Karen) by Sonic Youth. It's a weirdly arty but touching depiction of Karen Carpenter's struggle with anorexia and bulimia, with Kim Gordon as Karen. It even includes a Barbie-like doll.

dreaming, dreaming of a girl like mehey what are you waiting for - feeding, feeding meI feel like I'm disappearing - getting smaller every daybut I look in the mirror - I'm bigger in every way

The Butterfly in the Brain continues Anker's investigation into the visualizing techniques available through high technology simulation: the microscope, the telescope, the MRI scan. The exhibition focuses on a dialogue of signs within the symmetrical (or virtually symmetrical) structures of chromosomes, the butterfly and the brain, all of which possess an axis copy. Through pictorial substitution, demarcation, and relocation Anker creates a body of work out of science-based data.

In addition to Anker, BRAINWAVE included the art of David Bowen, Steve Budington, Phil Buehler, Andrew Carnie, George Jenne, Daniel Marguiles and Chris Sharp, Fernando Orellana and Brendan Burns, Jamie O'Shea, SERU, Devorah Sperber, Naho Taruishi, and Dustin Wenzel. SOMEHOW by Trickster Theater was a theatrical tour of the Common Senses exhibition. A preview of the performance (held April 16-17) is below.

Brain images are believed to have a particularly persuasive influence on the public perception of research on cognition. Three experiments are reported showing that presenting brain images with articles summarizing cognitive neuroscience research resulted in higher ratings of scientific reasoning for arguments made in those articles, as compared to articles accompanied by bar graphs, a topographical map of brain activation, or no image. These data lend support to the notion that part of the fascination, and the credibility, of brain imaging research lies in the persuasive power of the actual brain images themselves. We argue that brain images are influential because they provide a physical basis for abstract cognitive processes, appealing to people’s affinity for reductionistic explanations of cognitive phenomena.

Who are the Beauty Brains?The Beauty Brains are a group of cosmetic scientists who understand what the chemicals used in cosmetics really do, how products are tested, and what all the advertising means.

Save the Date for 9th Annual NCRG Conference on Gambling and Addiction - November 16-18, 2008 in Las Vegas, Nevada

Join researchers, clinicians, regulators, policy makers and industry representatives from around the world in Las Vegas November 16 to 18 for NCRG’s conference on the latest developments in pathological gambling research and responsible gaming programming.

New trends in science and society are raising provocative questions about gambling addiction. Will the definition of “pathological gambling” change in the next edition of the DSM? Is technology a threat or a solution to public health? How can we make treatment and responsible gaming relevant to ethnic minorities? Are new drugs transforming the treatment of gambling disorders?

Poster abstracts are due on Sept. 2, 2008.

Posters should report on empirical research that examines topics related to the theme of this year's conference, "The Changing Landscape of Treatment, Responsible Gaming and Public Policy." The following topics will be covered: diagnosis of pathological gambling and DSM issues; public health policy on gambling; screening and brief interventions; treatment outcome research; Stages of Change theory; the impact of technology on gambling addiction; pharmacological management of gambling and substance use disorders; the social, economic and cultural impact of gambling; gambling and other risky behaviors among youth; responsible gaming programs; and culturally competent resources for ethnic minorities.

ABOUT NCRG: The National Center for Responsible Gaming is the only national organization exclusively devoted to funding research that helps increase understanding of pathological and youth gambling and find effective methods of treatment for the disorder. The NCRG is the American Gaming Association’s (AGA) affiliated charity.

Tuesday, June 03, 2008

There was nothing very interesting in Katherine P. Rankin’s study of sarcasm — at least, nothing worth your important time. All she did was use an M.R.I. to find the place in the brain where the ability to detect sarcasm resides. But then, you probably already knew it was in the right parahippocampal gyrus.

But of course. Otherbloggers have already posted about this story (so go on, read more about sarcasm, social cognition and theory of mind there). The original research findings have yet to appear as a full-length publication, but Rankin and her colleagues presented this work at the recent American Academy of Neurology meeting in Chicago.

The NYT article continues:

Although people with mild Alzheimer’s disease perceived the sarcasm as well as anyone, it went over the heads of many of those with semantic dementia, a progressive brain disease in which people forget words and their meanings.

“You would think that because they lose language, they would pay close attention to the paralinguistic elements of the communication,” Dr. Rankin said.

To her surprise, though, the magnetic resonance scans revealed that the part of the brain lost among those who failed to perceive sarcasm was not in the left hemisphere of the brain, which specializes in language and social interactions, but in a part of the right hemisphere previously identified as important only to detecting contextual background changes in visual tests.

“The right parahippocampal gyrus must be involved in detecting more than just visual context — it perceives social context as well,” Dr. Rankin said.

It's not as simple as all that, Rankin et al. note in their own abstract. Worse performance in the Sarcasm test was also associated with greater atrophy in other sectors of the right temporal lobe and in the right superior frontal gyrus. Moreover, a 2005 study[BBC link via Of Two Minds] implicated a network of brain regions, primarily right ventromedial prefrontal cortex[they could not assess the importance of the right temporal lobe in their study]:

The volunteers who had damage to their prefrontal lobes were unable to correctly interpret the sarcastic story, while all of the other participants could...

[Dr Shamay-Tsoory] said language areas on the left hand side of the brain interpret the literal meaning of words and the frontal lobes and the right side of the brain understand the social and emotional context.

An area called the right ventromedial prefrontal cortex then integrates the literal meaning with the social/emotional context, which will reveal any sarcasm.

"A lesion in each region in the network can impair sarcasm, because if someone has a problem understanding a social situation, he or she may fail to understand the literal language," she said.

Oh well, "whatever", nevermind. I couldn't get The Sarcasterizer to work, so there you go.

It's "certain" that nobody's gotten tired of the insincerity and detached irony that's so prevalent in today's "hip" discourse. There's nothing the the world quite as "thrilling" as stumbling across yet another Web page drenched in "disaffected" sarcasm. And "everybody's" constantly asking us where they can get "more" of this "precious" commodity.

OBJECTIVE: To investigate the structural neuroanatomy underlying neurodegenerative disease patients failure to understand sarcasm from dynamic vocal and facial paralinguistic cues. BACKGROUND: While sarcasm can be conveyed solely through contextual cues such as counterfactual or echoic statements, face-to-face sarcastic speech may be characterized by a specific paralinguistic profile that alerts the listener to interpret the utterance as ironic or critical, even in the absence of contextual information. DESIGN/METHODS: Ninety-one subjects (20 frontotemporal dementia, 11 semantic dementia [SemD], 4 progressive nonfluent aphasia, 28 Alzheimer's, 6 corticobasal degeneration, 9 progressive supranuclear palsy, 13 healthy older controls) were tested using the Social Inference-Minimal subtest of The Awareness of Social Inference Test (TASIT). Subjects watched brief videos depicting sincere or sarcastic communication and answered yes-no questions about the speakers intended meaning. RESULTS: All groups performed normally interpreting items on a Sincere control task, suggesting other cognitive impairments did not significantly account for Sarcasm task performance. Only the SemD group was impaired on the Simple Sarcasm condition. Subjects failing the sarcasm comprehension task performed more poorly on dynamic emotion recognition tasks, had more neuropsychiatric disturbances, but had better verbal and visuospatial working memory than patients who comprehended sarcasm. Voxel-based morphometry analysis of TASIT scores was performed using age, sex, total intracranial volume, and performance on the Sincere condition as covariates. Poorer sarcasm recognition correlated with right temporal lobe atrophy (anterior fusiform and parahippocampal gyrii, superior temporal sulcus), and atrophy to the right superior frontal gyrus and striatal structures (right caudate and left globus pallidus) (pless than 0.05, FWE). CONCLUSIONS/RELEVANCE: This study provides lesion data suggesting that the right posterior temporal lobe and dorsomedial frontal cortex are associated with recognizing and interpreting sarcastic irony using paralinguistic vocal and facial cues, consistent with functional imaging research examining neural correlates of voice prosody, facial emotion recognition, and perspective taking.

About Me

Born in West Virginia in 1980, The Neurocritic embarked upon a roadtrip across America at the age of thirteen with his mother. She abandoned him when they reached San Francisco and The Neurocritic descended into a spiral of drug abuse and prostitution. At fifteen, The Neurocritic's psychiatrist encouraged him to start writing as a form of therapy.